Vision care specialist normally use visual acuiity and visual sentivity as their major methods of testing the integrity of a apatient's visual system. Spatial distortions which can cause serious patient problems and indicate numerous disease processes are difficult to test with present techniques and therefore are often ignored to the detriment of the patient. We have developed a technique that tests for differences in spatial localization or image size between the two eyes. The elimination of interocular apparent movement by the subject is used to indicate similar localization or image size betwe3en the two eyes. The elimination of interocular apparent movement by the subject is u sed to indicate similar localization by the two eyes. The technique is fast, accurate, easy for the patient and does not require steropsis. We propose to use a newly designe apparatus for three purposes. 1. To quantify the field distortions produced by aniseikonia, aphakic lenses, and other special optical devices. 2. To map local field distortions produced by pathological conditions such as retinal tears, central serious retinopathy, glaucoma, pregressive myopia, as well as albinism and amblyopia. 3. To perfect an instrument that can be used as a wide field test of spatial distortions as well as precise eikonometer. In come cases the tests will merely demonstrate the extent of a problem. In other cases they could be very useful in diagnosis and in following the progress of a diseas process.